1. Field of the Invention
The present invention generally relates to light fixtures and, more particularly, is concerned with a light fixture assembly and an adapter ring therefor having exterior fastening arrangements.
2. Description of the Prior Art
Light fixtures may be used in a variety of different environments. Some environments may expose a fixture to water, extreme temperatures, flammable materials or other hazardous elements. Certain fixtures are specially made for use in such environments. The fixture typically includes a ballast housing and a mounting plate to secure the fixture to a support structure, such as a pole or building surface. An adapter ring is generally needed to attach incompatible ballast housings and mounting plates to one another, such as a later-designed ballast housing to an earlier-designed mounting plate or the ballast housing of one supplier to the mounting plate of another supplier.
A representative example of a light fixture having an adapter ring is disclosed in U.S. Pat. No. 5,477,442 to Self. The Self adapter ring has a fastening arrangement for removably securing the adapter ring to the mounting plate. The fastening arrangement includes a hinge bar on the adapter ring which is engageable with a hinge hook on the mounting plate, a threaded hole through a boss on the adapter ring diametrically opposite the hinge bar which aligns with a hole through an external bracket on the mounting plate, and a fastening screw that inserts through the hole in the mounting plate bracket and threads into the threaded hole in the adapter ring boss for attaching the adapter ring to the mounting plate. Since the threaded hole through the adapter ring boss passes from exterior to interior sides thereof, a pair of sealing washers are provided along the screw about opposite ends of the adapter ring hole in order to seal the interior of the fixture from the exterior environment at the location of the adapter ring hole.
A similar adapter ring was previously developed and sold in 1970 by Killark Electric Mfg. Company, now a division of Hubbell, Inc., the assignee of the present invention. A problem exists, however, with these prior art adapter ring designs. The mounting screw passes through the wall of the adapter ring from the exterior to interior sides thereof and thus must be sealed to prevent dust or liquid from entering the fixture.
Consequently, a need remains for an adapter ring which provides a solution to the aforementioned problem in the prior art without introducing any new problems in place thereof.